In the late forties, motorcycle racers Freddie Dixon and Rex McCandless were doing engineering work in between racing motorcycles. Dixon was soon working on developing a 4WD utility vehicle for the military under the auspices of Harry Ferguson Research Inc. This machine had a rear mounted 4 cylinder engine and powered all four wheels through 3 differentials. As the machine developed it got heavier and more complicated. McCandless thought he could do better. He went back to his shop and built his 4wd Manx powered racer as a test bed for his ideas (not just for fun). At the same time he worked on a utility vehicle variant. This machine, the Mule, had a rear mounted, fan cooled 500cc Norton Dominator twin which drove the rear wheels by chain, then using another chain and sprocket system drove the front wheels. The two centrally mounted drum brakes- later discs- are visible below. The drive was enclosed in a box frame. The Mule weighed only 800 lbs and in Harry Ferguson sponsored offroad tests, easily outperformed Jeeps, Land Rovers, tractors and the Harry Ferguson Research Inc. machine. When it finally did get stuck it was light enough that it could be extricated easily.
Harry Ferguson, seeing that this looked to be the more successful device, started supplying financing to this one too. He apparently was a very difficult man to deal with, and the two men could not reach a deal. McCandless showed the machine around to various other manufacturers but no one had the courage to take on Harry Ferguson. Eventually, McCandless gave up on trying to get the Mule manufactured. More here,